The application relates to an external drive unit (7) for an implantable heart assist pump. The proposed drive unit (7) comprises a motor (35) for driving the heart assist pump, wherein the motor (35)is connectable to the heart assist pump via a transcutaneous drive shaft (3). The drive unit (7) further comprises a heat spreader (19) comprising a contact surface configured to contact and/or directly contact and/or lie flat against a skin of a patient. The contact surface is connected or connectable with the motor (35) in a thermally-conductive manner to transfer heat generated by the motor (35) to tissue of the patient.